The primary goal of this research is to better understand the role that individual neurotransmitters plan in the processing of visual information and whether individual neurotransmitters may be major factors in visual deprivation. One major aim is to identify what neurotransmitters are preent in monkey dorsal lateral geniculate (LGN) and striate cortex, and then to delineate what position they play within the neuronal circuitry of these regions. Neuroanatomical techniques will be used for all studies. We have already documented the presence of the known neurotransmitters gamma amino butyric acid (GABA), serotonin and catecholeamines in both LGN and cortex, as well as the peptides substance P in LGN and neuropeptide Y in cortex. We will continue our work 1. to localize the source of these pathways by double labeling with retrogradelytransported 3H-GABA or horseradish peroxidase followed by light microscopic (LM) immunocytochemistry (Imc), 2. to identify the synaptic type and postsynaptic position of each transmitter using eletron microscopic (EM) Imc, and 3. to follow their prenatal and postnatal development in striate cortex using EM, LM and EM Imc, and LM receptor binding autoradiography. Using the same techniques, we also will study the possible deletion, increase or rearrangement of thse neurotransmitters in the LGN and cortex in animals that have been visually deprived by perinatal monocular lid suture or atropine and adult monocular enucleation. We have shown that perinatal monocular atropinization induces a deprivation specific for high spatial frequencies. Striate cortex in these monkeys shows an alteration in cytochrome oxidase (CO) staining patterns. We will determine what neurophile changes underlie this alteration by means of CO staining for LM and EM. LMImc of GABA localization and LMImc based on antisera to specific synaptic proteins. We also will continue to study this deprivation model using behavioral and eletrophysiological techniques to determine the functional changes which may lead to this processing deficiency. These studies will gain better understanding of the mechanisms that lead to normal and abnormal development in the primate visual system, with the goal of providing more insight into the treatment of children who suffer from visual deprivation.